First observations of low latitude whistlers using WHU ELF/VLF receiver system

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The recently developed high-quality WHU ELF/VLF receiver system has been deployed in Suizhou, China(geomagnetic latitude 21.81°N, longitude 174.44°E, L=1.16) to detect low latitude extremely-low-frequency(ELF: 0.3-3 k Hz) and very-low-frequency(VLF: 3-30 k Hz) emissions originating from either natural or artificial sources since February 2016. During the first-month operation of the receiver system, a total of 3039 clear whistlers have been recorded at this low latitude station with the majority(97.0%) occurring on 28 February and 1 March 2016. Observed whistlers manifest various types including single one-hop, echo train, multi-flash, and multi-path. They tend to intensify after local midnight, reach the peak around 04-05 LT, and then weaken quickly. Both features of lower cutoff frequencies of most whistlers below ~1.6 k Hz and almost uniform dispersion for many successive multi-flash whistlers suggest that these whistlers propagate along the geomagnetic field lines in the duct mode. The computed dispersion varies between ~15 s~(1/2) and 23 s~(1/2) for observed one-hop whistlers and is greater than 50 s~(1/2) for three-hop echo train whistlers, indicating that the whistlers observed at the Suizhou station are low latitude whistlers. The recently developed high-quality WHU ELF / VLF receiver system has been deployed in Suizhou, China (geomagnetic latitude 21.81 ° N, longitude 174.44 ° E, L = 1.16) to detect low latitude extremely-low-frequency k Hz) and very-low-frequency (VLF: 3-30 k Hz) emissions originating from either natural or artificial sources since February 2016. During the first-month operation of the receiver system, a total of 3039 clear whistlers have been recorded at this low latitude station with the majority (97.0%) occurring on 28 February and 1 March 2016. Observed whistlers manifest various types include single one-hop, echo train, multi-flash, and multi-path. They tend to intensify after local midnight, reach the peak around 04-05 LT, and then weaken quickly. Both features of lower cutoff frequencies of most whistlers below ~ 1.6 k Hz and almost uniform dispersion for many successive multi-flash whistlers suggest that these whistlers propagate along the geomagnetic field lines in the duct mod e. The computed dispersion varies between ~ 15 s ~ (1/2) and 23 s ~ (1/2) for observed one-hop whistlers and is greater than 50 s ~ (1/2) for three-hop echo train whistlers , indicating that the whistlers observed at the Suizhou station are low latitude whistlers.
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